Gas turbine engine



A. A. LOMBARD ETAL 2,682,363

GAS TURBINE ENGINE Filed Deo. 5, 1951 June 29, 1954 A. A. LOMBARD ETAL 2,682,363

GAS TURBINE ENGINE Filed Dec. 3, 1951 6 Sheets-Sheet 2 June 29, 1954 A. A. LOMBARD ETAL 2,682,363

` GAS TURBINE ENGINE Filed Dec:` 3, 1951 6 Sheets-Sheet 3 June 29, 1954 A. A. LOMBARD ETAL 2,682,363

GAS TURBINE ENGINE Filed Dec. 3, 1951 6 Sheets-Sheet 4 June 29, 1954- A.A.LOMBARD TAL GAS TURBINE ENGINE e sheets-sheet 5 Filed Deo. 3, 1951 lJune 29, 1954 Filed Dec. 3, 1951 A. A. LOMBARD ET AL GAS TURBINE ENGINE 6 Sheets-Sheet 6 Patented June 29, 1954 UNITED STATES PATENT OFFICE GAS TURBINE ENGINE 00ml) any Application December 3, 1951, Serial No. 259,526

Claims priority, application Great Britain December 8, 1950 12 Claims. l

This invention relates to gas-turbine engines, and more particularly to gas-turbine engines having axial-now compressors.

It is common practice to tap off air compressed in a compressor of the gas-turbine engine for aux.. iliary purposes, for instance for the prevention, retardation or removal of ice formation on parts of an aircraft in which the engine is installed, and it is an object of the present invention to provide means whereby air may be tapped-off from the engine working uid duct and desirable air flow characteristics maintained within the engine.

According to this invention, a gas-turbine engine of the type having an axial-flow compressor, an inner duct-d-ening wall and an outer ductdening wall at the outlet of said compressor, and a plurality of hollow strut-like members interconnecting said inner wall and said outer wall and dividing part at least of the working fluid duct between the walls into a plurality of axiallyextending passages each bounded by a part of said inner wall, by a part of said outer wall, and by two adjacent strut-like members, is characterised in that a pair of adjacent strut-like members have apertures formed therein, which apertures are substantially symmetrically disposed with respect to the plane of symmetry of the passage between the pair of adjacent strut-like members, and which apertures are arranged to allow air to flow from the duct into the interiors of the pair of strut-like members, and outlet means communicating with the interiors of the strut-like members.

According to a preferred feature of this invention, a further wall is provided which is coaxial with the inner and outer duct-defining walls and co-operates with one of them to form annular collector manifold means. The annular collector manifold means may be arranged to provide a number of separate sources of tapped-off air by being divided by circumferentially-spaced walls into a number of sections or by circinnferentiallyextending walls. Likewise the hollow interiors of the struts may be divided by partitions into a number of chambers and it may be arranged that some of the strut-like members have air tapping apertures leading to the chamber upstream of the partition and others may have air-tapping apertures leading to the chambers downstream comprising an axial-flow compressor, the description making reference to the accompanying drawings in which- Figure l is an axial section through one embodiment,

Figure 2 is a section on the line 2 2 of Figure l,

Figure 3 is a section on the line 3-3 of Figure 2,

Figure 4 is a View corresponding to Figure l of the second embodiment,

Figures 5 and 6 show details being sections on the line 5 5 of Figure 4 through similar parts of the embodiment,

Figures 7 and 8 are diagrammatic sections through the embodiment of Figure 4 drawn to a i smaller scale, the sections being taken on axially spaced planes at right angles tothe axis of the embodiment, and

Figure 9 is a developed section on the line 9-9 of Figure 7.

In a gas-turbine engine, the working iluid is compressed by the compressor and is delivered from the compressor to combustion equipment wherein fuel is burned with the air, and the products of combustion pass from the combustion equipment to a turbine which is connected to the compressor by a shaft to drive it. The exhaust gas from the turbine passes to atmosphere via a propelling nozzle as a propulsive jet, or energy in excess of that required to drive the compressor or compressors is extracted from the products of combustion by the same or another turbine and used, for example, to drive a propeller or a power output shaft.

Referring now to Figures 1 to 3, the compressor, only the outlet end of which is shown, is illustrated as comprising a rotor assembly and a stator assembly, the rotor assembly including a drum or a number of discs such as disc I0 and having rows of rotor blades II mounted at its periphery, and the stator assembly including a stator casing i2 surrounding the rotor blades and rows of stator blades I3 mounted to extend inwardly from the stator casing I2; the rotor blade rows I I and stator blade rows i3 alternate along the length of the compressor. The stator casing I2 is usually split along a diametral plane. The rotor assembly IIl, Ii and stator assembly I2, I3 together define an annular duct in which the working iluid is compressed by the action of the blades.

A diffuser chamber casing I4 is bolted to the stator casing I2. The diffuser chamber casing Ibi comprises an inner annular wall I5 and an outer annular wall I6 joined together by a number of radial struts I'I. The two annular walls I5, I6 denne an annular duct which registers at its inlet end with the outlet end of the annular duct through the compressor. A labyrinth seal arrangement I8 is provided between the inlet end part of the inner annular wall I5 and the end compressor rotor disc I to minimise the escape of compressed air from the ducts where they Join.

The radial struts I1 have their upstream edges located downstream of the inlet end of the diffuser chamber casing I 4 and are integral with both the inner and outer walls I5, IS. The struts I1 divide the annular duct afforded between the walls I5, I5 into an equal number of circumferentially-spaced, axially-extending passages 29 (Figure 3), which passages 20 are of generally increasing cross-sectional area in the direction of flow of the air through them.

The combustion equipment of the gas-turbine engine may, as is well-known, comprise an annular combustion chamber formed by inner and outer air casing walls 2|, 22 respectively which encircle the shaft (not shown) connecting the compressor rotor and a turbine of the engine and a plurality of flame tubes 2 3 (Figure 3) disposed within the annular space between the air casing walls 2I, 22. Or, as is also well-known, the combustion equipment may comprise an annular combustion chamber formed by inner and outer air casing walls which encircle the shaft between a compressor and turbine, and an annular name tube disposed Within the annular space between the casing walls substantially coaxially with the air casing walls. Or, as is also well-known the combustion equipment may comprise a plurality of separate combustion chambers each having a tubular air casing and a substantially coaxial flame tube accommodated within the air casing in spaced relation thereto.

In a gas-turbine engine having either of the first two forms of combustion equipment described above, the inner and outer walls I5, I5 of the diffuser chamber casing It will, as shown, be arranged to be connected as by bolts to the inner and outer air casing walls 2i, 22. In the arrangement shown, the plurality of flame tubes 23 have their inlet ends conveniently spaced circumferentially to be aligned centrally with the axially-extending passages of the diffuser chamber casing i4, and a fuel injector 243 is provided for each llame tube 23. If a single annular flame tube is provided, the spacing of associated fuel injectors will preferably be correlated with the position of the passages 2i); for example, one fuel injector may be supported between each pair of radial struts I1. In these forms of combustion equipment, the struts I1 may conveniently terminate just upstream of the downstream end of the diffuser chamber casing I 4 so that the outlet from the diffuser chamber casing is a complete annulus.

In a gas-turbine engine having the third form of combustion' equipment described above, the diffuser chamber casing will, as is well understood, be formed at its outlet end with a number of branches to correspond with the number of combustion chambers, the branches each forming a generally axial extension of an axial passage 20. Each radial strut, corresponding to a strut I1, will at its downstream end divide to provide one side wall of each of the two adjacent branches, the inner and outer walls of a branch being formed by continuations of the inner and outer Vannular walls of the diffuser chamber casing. A branch will conveniently change in crosssection from a sector of an annulus at its upstream end to a circle at its downstream end and the outlet will register with the inlet of the associated air casing.

The upstream ends of the flame tubes and the downstream ends of the struts may overlap in the axial direction, and the upstream ends of the combustion chambers may be supported as shown in Figure 3 by being engaged with an annular seating 35a at the outlet end of a duct part 35 the function of which is to divide the air dowing in the passages such as the passages 20 into two streams, one of which streams passes through the duct part 35 into the inlet end of the flame tube 23 and the other of which streams flows outside the duct part 35 and outside the flame tube 23 to enter it through holes in the wall of the flame tube in a Well-known manner. The duct part 35 has formed in one piece with it a radially-extending part 36 which carries at its inner end the fuel nozzle 24 and at its outer end may provide a support for the duct part 35 by which it is attached to the wall I6.

It is sometimes required to tap-off compressed air from the working fluid passage of the engine, and the invention provides means for effecting such tapping of air.

In the arrangement of Figures 1 to 3, each radial strut I1 is made as a hollow shell having formed in its Walls a pair of apertures 25, there being one aperture 25 in each of its circumferentially-directed walls at approximately the point of greatest thickness of the strut I1. Thus air which has been compressed in the compressor flows into a strut IT from each of the axiallydirected passages 20 separated by the strut, or in other words air ows from each passage 2D through a pair of apertures 25 one in each of the struts I1 which separate the passage 20 from the next adjacent passages 20.

An annular collector manifold is formed by providing a pair of axially-spaced anges 26, 21 to upstand from the inner face of the inner annular Wall I5 of the diffuser chamber casing I4, and a co-operating annular part 2B which is bolted to the flange 26 and is in sealing engagement with an axially-directed portion of the other flange 21. The interior of each strut I 1 is in communication at its radially inner end with the manifold 29 and the compressed air flowing from the passages 20 through the apertures 25 into the hollow struts I1 flows from the struts I1 into the manifold duct 29. One of the struts I1 (that seen in Figure 1) opens at its radially outer end to an outlet port 3| which is bounded peripherally by a facing 30 formed on the outer surface on the outer annular wall I6.

An outlet conduit 32 is secured to the facing to register with the outlet port 3I and compressed air thus flows from the manifold 29 through the outlet conduit 32 to be conveyed to the point where it is desired to use the air. Two or more outlet conduits 32 may be provided if desired.

The interior of a hollow strut I1 may be divided into two or more chambers, for instance as are the right-hand and left-hand struts I1 (Figure 3) and those chambers through which air is not tapped off may be used as breather passages for the interior of the engine, or for example to permit auxiliary drive shafts to extend therethrough.

It is important that the velocity distribution of the air at the entry to the combustion equipment should be as uniform as possible and should remain so, irrespective of changes in operating conditions. It will be seen that this desideratum lis met by the construction of the invention, inthat the quantity of air tapped off for auxiliary purposes may be varied over a wide range without upsetting the distribution of the air owing into the combustion equipment.

As indicatedabove, the air tapped-off may be conveyed away through two or more outlets connected with the struts I 1.

Referring now to Figures 4 to 9, there are illustrated other ways in which more than one tapping may be effected. Other features are also shown.

In this arrangement, the diffuser chamber casing I4 comprises asbefore inner and outer walls 45, 46 respectively, which define an annular compressed air duct which is divided up into a number of passages 20 by a corresponding number (say eight) of hollow struts 41a, 41h, 41e, 41d, 41e, 41j, 41g, 41h.

Each strut has its interior divided by a partition 5E) into two chambers 48, 49 (see Figures 4, 5, 6 and 9) and the chambers 48, 49 communicate respectively with annular collector manifolds 5|, 52 which are formed between inner working-fluid duct wall 45 and a further wall 53, which is in one piece with the diffuser chamber casing, and which manifolds are separated by a radial web 53a extending circumferentially around the diffuser chamber casing between the walls 45, 52 at the axial location of the partition 5l).

The struts have slots formed in their circumferentially facing walls to permit compressed air to flow into one of the Chambers 48, 49. Thus some struts, say the struts 41h, 41e, 41d, 41j, 41g, 41h, are formed, as shown in Figure 6, with slots 54 4which are located just upstream of their partitions 58 and so feed air via chamber 48 into manifold 5|, and-other struts, say the struts 41a and 41e, have slots 55 formed in them (see Figure 5) just downstream of their partitions 50 and so feed air via chambers 49 into the manifold 52.

l'n the arrangement shown, the air is drawn off from the manifolds 5I, 52 either through outlets from the outer ends of a chamber 48 or 49 which has no slots 54 or 55 opening into it, or from outlets in a slotted chamber. Thus an outlet 51 is provided from chamber 48 of strut 41e through which air is drawn from manifold 5i, and in the case of strut 41e (Figures 8, 9) air is drawn off via chamber 49 from manifold 52.

If necessary an annular manifold may be divided into a number of part-annular take-off sections permitting two separate supplies from one diffuser chamber casing. Thus, as will be seen in Figures '1 and 9, the upstream manifold 5I is divided into a number of sections by axial partitions 58, one section communicating with the chamber 48 of strut 411) which is also formed with its outlet 51 at the outer end of the chamber 48, a second section communicating with chambers 48 of struts 41a., 41h, of which chamber 48 of strut 41h forms the air inlet and strut 41a. is provided with the air outlet 51, and a third section which is fed with air from the chambers 48 of the struts 41e, 41d, 41f and 41g and has its outlet through chamber 43 of strut 41e which leads to an outlet 51.

The annular manifold including walls 45, 46 may be formed by casting, and in this case the chambers 48, 49 may be formed by means of cores. The cores must be supported through apertures in the boundary walls of the chamber, and these are closed by means of core plugs 59 (Figures 4 and 5).v The apertures may be employed to permit an auxiliary shaft to extend through the diffuser chamber casing into the interior of the engine.

The invention is not limited to the particular embodiments described with reference to the drawings; for example, a strut may have a single air tapping aperture in its leading edge, provided that the apertures are symmetrically disposed with respect to the axially-directed passages 21). In this case it may be found desirable also to provide an aperture at the trailing edge through which pressure air is allowed to lead, to maintain the desired air ow characteristics.

ln another arrangement of the invention, each of the struts has formed in it two apertures, one in each of its circumferentially-directed faces, whereby the interior of the strut is placed in communication with the axially-extending passages on each side of the member.

In yet another arrangement of the invention as applied to a .gas-turbine engine having an even number of struts, each strut is formed with a single aperture in one of its circumferentiallydirected walls, the apertures being so arranged that they are in oppositely-directed walls in adjacent struts. In such an arrangement, therefore, alternate passages will have a pair of apertures one opening into each of the pair of struts which separate the passage from the next adjacent passages. These next adjacent passages will have no apertures in their boundry walls.

The apertures which open into the struts may be of different sizes provided that the two apertures which are formed one in each of the boundary walls of the passage into which they open are substantially of the same size.

We claim:

1. A gas-turbine engine comprising an axial ow compressor, an inner-duct-dening wall and an outer duct-defining wall at the outlet of said compressor, and a plurality of hollow strutlike members interconnecting said inner wall and said outer wall and dividing part at least of the working-fluid duct between the walls into a plurality of axially-extending passages each bounded by a part of said inner wall, by a part oi said outer wall, and by two adjacent strut-like members, characterised in that a pair of adjacent strut-like members have apertures formed therein, which apertures are substantially symmetrically disposed with respect to the plane of symmetry of the passage between the pair of adjacent strut-like members, and which apertures are arranged to allow air to flow from the duct into the interiors of the pair of strut-like members, there being provided also outlet means communicating with the interiors of the strutlike members.

2. A gas-turbine engine as claimed in claim 1, having an even number of strut-like members each formed with a single aperture in one of its circumferentially-directed walls, the apertures being so arranged that they are in oppositelydirected walls in adjacent strut-like members.

3. A gas-turbine engine as claimed in claim 1, having only two of its plurality of strut-like members apertured, each of said two strut-like members being formed with one aperture in one of its circumferentially-directed Walls, the two strut-like members being adjacent members and the apertured walls being the boundary walls of the duct passage between the two strut-like members.

4. A gas-turbine engine comprising an axialflow compressor, an inner-duct-dening wall and an outer duct-defining wall at the outlet of 7 said compressor, and a plurality of hollow strutlike members interconnecting said inner wall and said outer wall and dividing part at least of the working-fluid duct between the walls into a plurality of axially-extending passages each bounded by a part of said inner wall, by a part of said outer wall, and bytwo adjacent strutlike members, characterised in that a pair of adjacent strut-like members have apertures formed therein, which apertures are substantially symmetrically disposed with respect to the plane of symmetry of the passage between the pair of adjacent strut-like members, and which apertures are arranged to allow air to flow from the duct into the interiors of the pair of strutlike members, and in that there is also provided a further wall coaxial with said inner and outer walls and outside said duct, which further wall co-operates with one of said duct-dening walls to form annular collector manifold means communicating with the interiors of the strut-like members to receive tapped-oil air therefrom, and outlet means communicating with the interiors of the strut-like members.

5. A gas-turbine engine as claimed in claim 4, wherein said further wall is bolted to a ilange extending radially inwards from the inner ductdening wall and co-operates in a gas-sealing manner with a second and axially-spaced ange extending inwardly from said inner duct-dening wall.

6. A gas-turbine engine as claimed in claim 4, wherein said inner and outer duct-dening walls, said strut-like members and said further wall are formed in one piece with one another.

7, A gas-turbine engine as claimed in claim 4, wherein the outlet means communicates with the manifold means through the hollow interior of a strut-like member.

8. A gas-turbine engine comprising an axialnew compressor, an inner-duct-dening wall and an outer duct-dening wall at the outlet of said compressor, and a plurality of hollow strutlike members interconnecting said inner wall and said outer wall and dividing part at least of the working-uuid duct between the walls into a plurality of axially-extending passages each bounded by a part of said inner wall, by a part of said outer wall, and by two adjacent strutlilze members, characterised in that a plurality of pairs of adjacent strut-like members have apertures formed therein, the apertures which open into a passage between a pair of adjacent strut-like members being substantially symmetrically disposed with respect to the plane of symmetry of said passage and which apertures are arranged to allow air to flow from the duct into the interiors of the pairs of strut-like members, in that the hollow strut-like members are divided internally by partitions into upstream and downstream chambers, some of said strutlike members having their air tapping apertures upstream of the partition and others having their air tapping apertures downstream of their partitions and in that there is also provided a further wall coaxial with said inner and outer walls and outside said duct, which further wall co-operates With one of said duct-defining walls to form annular collector manifold means communicating with the interiors of the strut-like members to receive tapped-oit air therefrom and to aord at least two separate sources of tappedofr air, and outlet means communicating with the annular collector manifold means.

9. A gas-turbine engine as claimed in claimv 8, wherein said annular collector manifold means is divided to afford at least two collector manifolds by a circumferentially-extending web which extends radially from said further wall to the co-operating duct-defining wall at the axial location of the partitions which divide the interiors of the hollow strut-like members into separate chambers.

10. A gas-turbine engine as claimed in claim 8, having said outlet means arranged to communicate with one of said chambers in the divided interior of a strut-like member at the end of the chamber remote from the associated annular collector manifold means.

11. A gas-turbine engine as claimed in claim 8, wherein the outlet means communicate with one of the said chambers in the divided interior of a strut-like member on the Side of the dividing partition remote from the air-tapping apertures in said strut-like member, and at the end of the chamber remote from the associated annular collector manifold means.

12. A gas-turbine engine comprising an axialflow compressor, an inner annular duct-dening wall and an outer annular duct-defining wall at the outlet of said compressor, and a plurality of substantially radial, hollow strut-like members interconnecting said inner annular wall and said outer annular wall and dividing part at least of the Working fluid duct between the walls into a plurality of axially-extending passages each bounded by a part of said inner wall, by a part of said outer wall, and by two adjacent strut-like members, characterised in that each of said strut-like members has a pair of apertures formed therein, which apertures are substantially symmetrically disposed with respect to the planes of symmetry of each passage between adjacent pairs of strut-like members, and which apertures are arranged to allow air to now from the duct into the interiors of said strut-like members, and outlet means communieating with the interior of the strut-like members.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,314,058 Stalker Mar. 16, 1943 2,344,835 Stalker Mar. 21, 1944 2,469,375 Flagle May 10, 1949 FOREIGN PATENTS Number Country Date 619,390 Great Britain Mar. 8, 1949 959,401 France Sept. 26, 1949 

